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 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.lang.invoke;

import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.org.objectweb.asm.Type;
import sun.invoke.util.BytecodeDescriptor;
import sun.invoke.util.Wrapper;

import static sun.invoke.util.Wrapper.*;

class TypeConvertingMethodAdapter extends MethodVisitor {

  TypeConvertingMethodAdapter(MethodVisitor mv) {
    super(Opcodes.ASM5, mv);
  }

  private static final int NUM_WRAPPERS = Wrapper.values().length;

  private static final String NAME_OBJECT = "java/lang/Object";
  private static final String WRAPPER_PREFIX = "Ljava/lang/";

  // Same for all primitives; name of the boxing method
  private static final String NAME_BOX_METHOD = "valueOf";

  // Table of opcodes for widening primitive conversions; NOP = no conversion
  private static final int[][] wideningOpcodes = new int[NUM_WRAPPERS][NUM_WRAPPERS];

  private static final Wrapper[] FROM_WRAPPER_NAME = new Wrapper[16];

  // Table of wrappers for primitives, indexed by ASM type sorts
  private static final Wrapper[] FROM_TYPE_SORT = new Wrapper[16];

  static {
    for (Wrapper w : Wrapper.values()) {
      if (w.basicTypeChar() != 'L') {
        int wi = hashWrapperName(w.wrapperSimpleName());
        assert (FROM_WRAPPER_NAME[wi] == null);
        FROM_WRAPPER_NAME[wi] = w;
      }
    }

    for (int i = 0; i < NUM_WRAPPERS; i++) {
      for (int j = 0; j < NUM_WRAPPERS; j++) {
        wideningOpcodes[i][j] = Opcodes.NOP;
      }
    }

    initWidening(LONG, Opcodes.I2L, BYTE, SHORT, INT, CHAR);
    initWidening(LONG, Opcodes.F2L, FLOAT);
    initWidening(FLOAT, Opcodes.I2F, BYTE, SHORT, INT, CHAR);
    initWidening(FLOAT, Opcodes.L2F, LONG);
    initWidening(DOUBLE, Opcodes.I2D, BYTE, SHORT, INT, CHAR);
    initWidening(DOUBLE, Opcodes.F2D, FLOAT);
    initWidening(DOUBLE, Opcodes.L2D, LONG);

    FROM_TYPE_SORT[Type.BYTE] = Wrapper.BYTE;
    FROM_TYPE_SORT[Type.SHORT] = Wrapper.SHORT;
    FROM_TYPE_SORT[Type.INT] = Wrapper.INT;
    FROM_TYPE_SORT[Type.LONG] = Wrapper.LONG;
    FROM_TYPE_SORT[Type.CHAR] = Wrapper.CHAR;
    FROM_TYPE_SORT[Type.FLOAT] = Wrapper.FLOAT;
    FROM_TYPE_SORT[Type.DOUBLE] = Wrapper.DOUBLE;
    FROM_TYPE_SORT[Type.BOOLEAN] = Wrapper.BOOLEAN;
  }

  private static void initWidening(Wrapper to, int opcode, Wrapper... from) {
    for (Wrapper f : from) {
      wideningOpcodes[f.ordinal()][to.ordinal()] = opcode;
    }
  }

  /**
   * Class name to Wrapper hash, derived from Wrapper.hashWrap()
   *
   * @return The hash code 0-15
   */
  private static int hashWrapperName(String xn) {
    if (xn.length() < 3) {
      return 0;
    }
    return (3 * xn.charAt(1) + xn.charAt(2)) % 16;
  }

  private Wrapper wrapperOrNullFromDescriptor(String desc) {
    if (!desc.startsWith(WRAPPER_PREFIX)) {
      // Not a class type (array or method), so not a boxed type
      // or not in the right package
      return null;
    }
    // Pare it down to the simple class name
    String cname = desc.substring(WRAPPER_PREFIX.length(), desc.length() - 1);
    // Hash to a Wrapper
    Wrapper w = FROM_WRAPPER_NAME[hashWrapperName(cname)];
    if (w == null || w.wrapperSimpleName().equals(cname)) {
      return w;
    } else {
      return null;
    }
  }

  private static String wrapperName(Wrapper w) {
    return "java/lang/" + w.wrapperSimpleName();
  }

  private static String unboxMethod(Wrapper w) {
    return w.primitiveSimpleName() + "Value";
  }

  private static String boxingDescriptor(Wrapper w) {
    return String.format("(%s)L%s;", w.basicTypeChar(), wrapperName(w));
  }

  private static String unboxingDescriptor(Wrapper w) {
    return "()" + w.basicTypeChar();
  }

  void boxIfTypePrimitive(Type t) {
    Wrapper w = FROM_TYPE_SORT[t.getSort()];
    if (w != null) {
      box(w);
    }
  }

  void widen(Wrapper ws, Wrapper wt) {
    if (ws != wt) {
      int opcode = wideningOpcodes[ws.ordinal()][wt.ordinal()];
      if (opcode != Opcodes.NOP) {
        visitInsn(opcode);
      }
    }
  }

  void box(Wrapper w) {
    visitMethodInsn(Opcodes.INVOKESTATIC,
        wrapperName(w),
        NAME_BOX_METHOD,
        boxingDescriptor(w), false);
  }

  /**
   * Convert types by unboxing. The source type is known to be a primitive wrapper.
   *
   * @param sname A primitive wrapper corresponding to wrapped reference source type
   * @param wt A primitive wrapper being converted to
   */
  void unbox(String sname, Wrapper wt) {
    visitMethodInsn(Opcodes.INVOKEVIRTUAL,
        sname,
        unboxMethod(wt),
        unboxingDescriptor(wt), false);
  }

  private String descriptorToName(String desc) {
    int last = desc.length() - 1;
    if (desc.charAt(0) == 'L' && desc.charAt(last) == ';') {
      // In descriptor form
      return desc.substring(1, last);
    } else {
      // Already in internal name form
      return desc;
    }
  }

  void cast(String ds, String dt) {
    String ns = descriptorToName(ds);
    String nt = descriptorToName(dt);
    if (!nt.equals(ns) && !nt.equals(NAME_OBJECT)) {
      visitTypeInsn(Opcodes.CHECKCAST, nt);
    }
  }

  private boolean isPrimitive(Wrapper w) {
    return w != OBJECT;
  }

  private Wrapper toWrapper(String desc) {
    char first = desc.charAt(0);
    if (first == '[' || first == '(') {
      first = 'L';
    }
    return Wrapper.forBasicType(first);
  }

  /**
   * Convert an argument of type 'arg' to be passed to 'target' assuring that it is 'functional'.
   * Insert the needed conversion instructions in the method code.
   */
  void convertType(Class<?> arg, Class<?> target, Class<?> functional) {
    if (arg.equals(target) && arg.equals(functional)) {
      return;
    }
    if (arg == Void.TYPE || target == Void.TYPE) {
      return;
    }
    if (arg.isPrimitive()) {
      Wrapper wArg = Wrapper.forPrimitiveType(arg);
      if (target.isPrimitive()) {
        // Both primitives: widening
        widen(wArg, Wrapper.forPrimitiveType(target));
      } else {
        // Primitive argument to reference target
        String dTarget = BytecodeDescriptor.unparse(target);
        Wrapper wPrimTarget = wrapperOrNullFromDescriptor(dTarget);
        if (wPrimTarget != null) {
          // The target is a boxed primitive type, widen to get there before boxing
          widen(wArg, wPrimTarget);
          box(wPrimTarget);
        } else {
          // Otherwise, box and cast
          box(wArg);
          cast(wrapperName(wArg), dTarget);
        }
      }
    } else {
      String dArg = BytecodeDescriptor.unparse(arg);
      String dSrc;
      if (functional.isPrimitive()) {
        dSrc = dArg;
      } else {
        // Cast to convert to possibly more specific type, and generate CCE for invalid arg
        dSrc = BytecodeDescriptor.unparse(functional);
        cast(dArg, dSrc);
      }
      String dTarget = BytecodeDescriptor.unparse(target);
      if (target.isPrimitive()) {
        Wrapper wTarget = toWrapper(dTarget);
        // Reference argument to primitive target
        Wrapper wps = wrapperOrNullFromDescriptor(dSrc);
        if (wps != null) {
          if (wps.isSigned() || wps.isFloating()) {
            // Boxed number to primitive
            unbox(wrapperName(wps), wTarget);
          } else {
            // Character or Boolean
            unbox(wrapperName(wps), wps);
            widen(wps, wTarget);
          }
        } else {
          // Source type is reference type, but not boxed type,
          // assume it is super type of target type
          String intermediate;
          if (wTarget.isSigned() || wTarget.isFloating()) {
            // Boxed number to primitive
            intermediate = "java/lang/Number";
          } else {
            // Character or Boolean
            intermediate = wrapperName(wTarget);
          }
          cast(dSrc, intermediate);
          unbox(intermediate, wTarget);
        }
      } else {
        // Both reference types: just case to target type
        cast(dSrc, dTarget);
      }
    }
  }

  /**
   * The following method is copied from
   * org.objectweb.asm.commons.InstructionAdapter. Part of ASM: a very small
   * and fast Java bytecode manipulation framework.
   * Copyright (c) 2000-2005 INRIA, France Telecom All rights reserved.
   */
  void iconst(final int cst) {
    if (cst >= -1 && cst <= 5) {
      mv.visitInsn(Opcodes.ICONST_0 + cst);
    } else if (cst >= Byte.MIN_VALUE && cst <= Byte.MAX_VALUE) {
      mv.visitIntInsn(Opcodes.BIPUSH, cst);
    } else if (cst >= Short.MIN_VALUE && cst <= Short.MAX_VALUE) {
      mv.visitIntInsn(Opcodes.SIPUSH, cst);
    } else {
      mv.visitLdcInsn(cst);
    }
  }
}
